1. Field of the Invention
The invention relates to food product cans provided with can end members which may be opened easily by tearing a panel portion of the end along a score line with a ring pull tab. More particularly the invention relates to such can ends fabricated from light gauge steel from which the torn panel portion when torn leaves a substantially full opening in the can end. The pull tab is riveted to the panel portion to be torn and is formed of aluminum. Tearing proceeds along the score line located in the steel end very close to a usual double seam which connects the can end to one end of a generally cylindrical steel can body. The score line preferably extends less than 360.degree., say 300.degree., around the can end adjacent the double seam, so that the torn panel portion remains connected with the can end at the opening thus formed with the pull tab connected thereto.
Also, the invention relates to the described steel can end in which the periphery of the torn panel portion is formed with a protective triple fold generally of the type shown in U.S. Pat. No. 4,116,360 wherein the score line is located in the top triple fold layer, and the can end is initially ruptured on the score line by the nose or tip of a pull tab generally of the type shown in U.S. Pat. No. 4,042,144.
In addition, the invention relates to the described steel can end with an aluminum pull tab riveted thereto having special rivet characteristics imparted during rivet formation combined with a specially shaped and located moustache type score adjacent the rivet to assist in ease of opening the can end without tearing the pull tab from the panel portion being torn from the can end when the can is being opened.
Finally, the invention relates to a new steel can end construction described in detail below involving an interrelation of the forms, shapes, compositions, characteristics and cooperative arrangements of the various components combined to form the new can end.
2. Description of the Prior Art
Steel can ends for beverage cans are known having small teardrop- or keyhole-shaped pouring openings formed in the can end wall by pulling keyhole-shaped metal completely from the can end with a pull tab attached to the removed metal.
Also, beverage cans are known which have pull tabs attached to torn teardrop metal portions, both of which remain attached to the can after forming the pouring opening. In general, the torn out metal portion remains inside the can and there is no protective edge formation on such torn metal portion inside the can. Some of such prior can ends may have been made from steel but it is exceedingly hard or difficult to open such steel can ends.
Still another steel can end seamed to a steel can and provided with a steel pull tab having a so-called moustache cut behind the rivet is known. Such a can end is exceedingly hard and difficult to open. Such prior steel cans are intended to provide a full opening by completely tearing a panel portion from the can to form a full opening. The torn out panel portion has a protective edge formed by a peripheral triple fold.
The score line in this prior device is located in the bottom layer of the triple fold below and concealed by the reversely bent two top triple fold metal layers. The panel portion to be removed extends from and in the plane of the top layer of the triple fold. Such particular score line location and triple fold arrangement in said prior device is believed to contribute among other matters to the great difficulty encountered in opening such a can end. Frequently, in attempting to open such prior device with the steel pull tab riveted thereto, the pull tab tears away from the can end leaving the can unopened.
We are not aware of any prior art steel can end from which a full or substantially full opening panel may be very easily torn along an opening-defining score line with an aluminum pull tab riveted to the panel to be torn, and in which the torn panel portion has a protective triple fold formation along its torn edge.
Accordingly, there is an existing need in the art for full opening cans provided with steel can ends which may be easily opened with an aluminum pull tab riveted to a full or substantially full opening panel portion by tearing along a score line located close to a seam between the can end and can body, and in which the torn panel portion has a protective triple fold formation along its peripheral edge.